Method of making closure caps



NOV. 7, 1944. Y| A; VON T|| 2,362,421l

METHOD OF MAKING 'CLOSURE CAPS Filed March 12, 1941 2 Sheets-Sheetl 'MMI INVENTOR www L. A. voN TILL METHOD 0F MAKINGl CLOSURE CAPS Nov. 7, 1944.

Filed March l2,l 1941 2 Sheets-Sheet new,

5 J WI ATTORNEY vture of .threadedclosures and threaded containers The thread projection on the glass container is Patented Nov. 7, 1944 Anchor Capf& ClosueiCorpoi-ation, Long VIsland City, N. Y., a corporation of -New York Application Marchpiz, 19

Y3 claims. 501.

.'Ihepresent invention Arela-tes more particularly. to annethod of making .closure caps.

Great diiiiculty '.has'sbeen .encountered in the closure Iand glass :container art in the manufac- `which will .mate properly. The -diiculty arises because neither closures nor yglass containers can -be made .accurately to specifications. In faddiztion, there vhas been a de'nite *limitation in `the distance that closure threads `lcon be rolled in- -wardly without rupturing `the metal. `Glass man- Auacturers follow specifications set up'by the Glass .Container Association which'allow tolerances of about .iorty-thousandths of an'inch 4vin l the diameter lof glass nishes of the seventy millimeter size. -This is fthe-size of lnishus'ed `for fruit jars and large size `jars of mayonnaise. C'ap manufacturers-are required tokeepwithin a tolerance of ten-thousandths vof van inch variation in Athe diameter yofthe Acap for thevabove 'size glass nnis'h. The maximum commercial depth-of screw threads on closure caps Aunder practices hereto- I fore has been forty-thousandths of 'an inch.

about Vsixty-thousandths `of an inch. y

A closure of minimum sizegmay be applied to a .jar of maximum size.. In .such instancesuthe closures must Vgo onand must `notfit too tight. If it fails to function properly, 'thepacker WillmanV complain. Likewise amaximum `cap may Lbe ap"'" V4plied to a minimum .size jar. YIllnsu'cha case it vmust not fit 'tooiloose `and-it must form `a good sea'l to prevent complaints. Inman-y .casesthe allowed tolerances .are .exceeded .becauseit is not 3 practical to .place a gauge on `either the indi-M vidual closures manufactured .orr .on `the 4individual glass containers.. vThey can only be checked at intervals with the assumption that .all of the unchecked V,closures and.. containers arel 40 in l accord with those checked. Ihusa closure or container may have variations which :exceed the allotted tolerances.. .Itis thereforeimportant that .closures .can .be adapted V,to accommodatef-maxi mum andminimum sizes-.of ,glass containers, and, if possible, variations `slightly `above .and ,below the prescribed tolerances. Usually' when the cap does .not ,-t ,properly jon Ythe container, the .thread .of the closure ,tends to ride over. the thread 1on .the .container whichcauses the cap to cock or jto bulge at one point. In either event an imperfect seal is formed and the closure is hard to remove. Another.difficulty is that .thethread on th'e container .ma-y vary slightly in its vertical position or it may be wavy. The clos-ure has to rmay 'be provided.

41, serial No. 382,903v

:accommodate such Avirregularities without 1matelrially .impairing 4the Asealing operation.

The present` invention aims to overcome or minimize the ,above difficulties byproviding a :method .of .manufacturing closures .in which the thread means maybe rolled deeper without rup- Ituring the metal iof the cap .and by providing 4a closure ,with thread projections having extraorydinary depth which will vbend. independently 4.in a vertical direction ywithout substantial distortion y,offthezskirt in a circumferential direction, and

otherwise to provide a more perfect t .between the `closure vand the container. .The invention 'aims .to accomplishxthe .above results without :an improved method of making closure caps by Awhich a vdeeper and more effective thread means Another object of the invention isto provide an' improved method of manufacturing closure front of the thread roller is formed into a reinforcing arch.

' Another object of the invention is to provide van improved method of rolling knurls in 'a threaded cap which will not interfere with the "application ofthe cap to a container.

Another object of theinvention is the provi- 4'sion of'a method of making -a closure cap having screw projections arranged substantially end to end which will yield independently in a vertical direction. v

Another object ofthe invention isthe provi- Vsionof a method of .making a closure cap havamethod of making a closure cap havingsectional .screw v.projections yieldable independently in a vertical direction with' the sections sulciently close to each other to prevent substantial circumferential deformation of the skirt.

Otherand further vobjects ofthe invention will be obvious upon an Vunderstanding of the illusrtrative embodiment about to be described, yor willv beindicated in the appended claims, and vvarious advantages not referred .to herein will occur to one skilled ,in 4the art f upon employment of the vinvention :in practice.

up of dough in front of a rolling pin.

ferred method of manufacture;

Fig. 4 is an enlarged fragmentary sectional view illustrating a minimum size closure applied -to a maximum size container; y

Fig. 5 is an enlarged fragmentary sectional view illustrating a maximum size closure applied to a minimum size container finish;

Fig. 6 is an enlarged fragmentary sectional` view taken intermediate the ends of two thread projections along the line 6--6 of Fig. '7;

Fig. '7 is a fragmentary elevational view of a portion of the inside of the skirt of the cap illustrating the thread projection;

Fig. 8 is a fragmentary sectional View lengthwise of the thread along the line 8-8 of Fig. "1;

Fig. 9 is a 'sectional view of a closure applied to a container having a wavy thread, the irregularities being shown in exaggerated form; and

Fig. l0 is an enlarged fragmentary view illustrating in exaggerated form the behavior of the metal of the closure in rolling the thread projection.

Referring again to the drawings, there is shown in Fig. 1 a hat-shaped blank having a blanks are then delivered to a rolling machine under the present method which rolls the flange 4 into a bead or wire edge 6. At the same time .the rolling tools form a groove 1 in the skirt of the cap adjacent the cover part thereof. 'I'hese grooves may be formed either by rolling the metal of the groove outwardly or by rolling the metal of theskirt below the groove inwardly. Preferably it is formed by rolling the metal in the groove outwardly as this simplifies the manufacture of the closure.

Thereafter threading tools engage the blank and roll a series of thread projections ID in the skirt of the cap separated by intermediate portions H which are preferably substantially arch shaped for the purposes described hereinafter. Preferably at the same time that the thread is being rolled the groove 1 has formed therein corrugations l2. These corrugations facilitate gripping the closure in the application and removal thereof and in addition improves the appearance thereof.

In the rolling of continuous spiral threads in a closure 'the metal piles up in front of the threading tool somewhat similarly to the piling In the manufacture of closures this piling up of metal is suiliciently great in some instances to cause the buckling of the metal under the roller. Also in rolling a continuous thread the metal has to be drawn from the two sides of the thread. It is entirely a stretching operation. Additional metal has to come from somewhere in pressing the thread groove in the skirt of the cap and the only place available is from the sides of the thread. In some instances manufacturers have tried to minimize the strain on the metal by permitting the skirt of the cap to collapse or shorten during the rolling operation thereby endeavoring to obtain an accordion effect. Such collapsing increases the amount of metal required in a closure of a given height and in addition prevents accurate control of both the shape and the depth of the thread. In addition the length of the skirt of the cap is decreased noticeably where the thread overlaps, there being two plaits where in the remainder of the skirt of the cap there is but one. The more common practice at the present time is to clamp the metal on the two sides of the thread to prevent a decrease in the height of the skirt and to draw the metal v, from the two sides of the thread. I have discovered that much deeper thread projections may` be formed by permitting the metal which piles up in front of the roller to form relatively short interruptions in the thread. In this way strain on the metal at the sides of the thread is relieved at short intervals and in addition the metal for the thread projections ymay be drawn from four directions where previously it has been drawn from two directions. In this way it has been found that the depth of the thread projections can be increased in commercial practice from the former depth of forty-thousandths of an inch to sixty-thousandths of an inch.

The mechanism for forming the thread may be varied, but a preferred form is shown in Fig. l0 wherein a large disc i4 has a thread rib I5 formed thereon with interruptions or identations IB at short intervals therein. Cooperating with the disc i4 is a chuck or a roller I1 of smaller size than the diameter of the cap which fits into the cap blank as illustrated in Fig. 10. The

metal as it begins to pile up in front of the roller as shown at I8 is permitted to bulge into the recesses I6 of the thread rib l5 thereby preventing excessive accumulation of metal in front of the roller and also minimizing the tendency of the metal to buckle in front of the roller at that point. In addition, as it will be noted in Fig. l0, the metal being forced inwardly into the projections may be drawn from four sides. The strains on the metal at the sides of the thread are relieved at the interruptions Il. By utilizing this method the depth 0f the thread may be increased substantially fifty percent without subjecting the metal to more than the customary amount of strain. In fact it has been found that fewer instances of rupture are encountered in the manufacture of the present closures with the increased depth of the thread than in the previous manufacture of continuous thread closures with a much less depth of thread. y The best results have been obtained with the present method and the best operation with the resulting closure by making the thread projections |0 about M; to of an inch in length with the intermediate interruptions il about 1/8 of an inch in length. It is to be understood that these dimensions may be varied within limits, but excellent results have been obtained with the above specifications.

The closure is shown applied to a container 28 y A in Figs. 4, 5 and 9, having a spiral thread 2| tain'erthrea'dil kand#theIinnerfside -of thefskiiitlof the fcap. Bylutill-zing applicartls method it iis 'possible tolincrease the Adepthoff the thread from :about '..rorty-thousandths 1fof :an-.finch to :sixty- 'thousandths therebyemakingzthe 'threadaproection in Afthe closure `.project inward-1y as .fiar aas the thread .Ion the container projects @outwardly :since :E'igliiilustrates a-zniinimum size- Icap oif-a maximum size container, the lclearancelbetween the lthreadof .theiconta'liner and the skirt of the cap aswell as the clearance between the thread of the cap and the wall of the container is small.

In Fig. the other extreme condition is shown in which a maximum size cap is placed on a min-V 4, closures are required to accommodate threads on the container which vary in height. In many cases the threads are wavy' as shown more particularly in Fig. 9 where the thread has a downward wave as shown at 24 and an upwardwave as shown at 22. The series of spirally arranged end to end projections I0 tend to act independently in a vertical direction. Hence when a wavy portion 22 is engaged, the individual projections will be bent downwardly to take care Vof theA irregularity. f

With a continuous type thread there would not be the same vertical flexibility. In addition the thread would be bent down for a substantial distance on each side of the downward projection. With the present closure a continuous holding contact is formed on the downward projection 22 and also at the sides thereof. The projections form in effect a chain or a series of spring tongues which adjust themselves to the irregularity of the thread and follow it around its underside.

One of the most troublesome problems encountered in sealing glass containers is the tendency for a closure to cock or buckle up on one side. The tendency of the closure thread to ride over the container thread forces the skirt outwardly which acts as a lever to bend the closure cover at that point upwardly. Such instances are very noticeable particularly with smaller closures and are quite objectionable because they impair the seal and cause spirited complaints by packers.

.In the present closure the interruptions between the projections Il) are sufficiently short'so that they form substantially arch-shaped portions Il and hence reinforce the closure in a circumferential direction and tend to prevent the projections IU from moving outwardly. The arch construction is a very strong one yand it has been found very effective in preventing distortion of the skirt in a circumferential direction andthe resulting cooking and bulging of the cover part of the cap about the sealing surface. The construction of the portions of the skirt intermediate the thread projections l0 is shown at Il in the fragmentary sectional view of Fig. 6 and also at Il in the enlarged elevational view in Fig. 7 and the horizontal sectional view in Fig. 8.

l'the wap. `The iupperfend fof the thread @rejec- Ztionffdoesnot engage the knurls. fof -the closure even ywhen a lininimum fsiz'e'cap :is 'applied Lto a fmaximumsize (container :as shownv 1in Fig. 4.

esula'stain-tiallyto the vthread von' the -container even when there are substantial irregularities therein and an effective seal will be provided and a minimum effort will be required in removing the closure.

It will be seen that the present invention provides an improved method of manufacturing closure caps in which screw threads of unusual depth may be formed. The method does not increase the amount of metal required in the closure or increase the cost of manufacture. In addition the resulting closure has an improved thread and will .take up a much greater variation in size of container than closures manufactured heretofore. The independent spirally arranged endvto end projections permit a greater depth of thread projection and in addition cooperate to conform to the underside of the thread of the container, thereby to make a more effective seal. 'I'he arch portions intermediate the thread projections reinforce the closure and minimize circumferential distortion and the resulting tendency of the closure to cock. The method'may be applied with minimum changes in existing machinery and hence can be introduced commercially at a minimum cost.

As various changes may be made in the form, construction and arrangement of the parts herein without departing from the spirit and scope of the invention and without sacrificing any of its advantages, it is to be understood that all matter herein is to be interpreted Vas illustrative and not in a limiting sense.

Having thus described my invention, I claim:

1. The method of making closure caps with a screw thread in a cylindrical skirt, which method comprises rolling inwardly, substantially to the limit of the stretching that the metal will withstand without rupture. a spirally arranged projection in the cylindrical skirt of the closure cap to form a part of theclosure thread, rolling a succeeding like projection of said threadat a selected distance from the end of the first projection to leave the excess metalv in front of the roller in the intermediate portion, thereby to reduce the strain on the metal in the projection yand also to a greater extent the strain on the Another feature of the closure is the eliminametal of the intermediate portion, and, in rollingy said like projection, drawing part of the material from the less strained intermediate portion into said succeeding like projection and repeat. ing said step to form the complete thread.

2. The method of making screw closure caps with screw projections in a cylindrical skirt which method comprises rolling radially inwardly an extraordinarily deep spiral groove on the exterior of the cylindrical skirt 'to form a screw thread portion on the interior of the skirt of the closure, and reducing the strain on the metal occasioned by metal piling up in front of the roller forming the groove by forming interruptions in the groove which take up the excess metal that pilesup in front of the roller and pulling part of the metal -for rolling each suc-v ceeding portion of the groove from the metal of the preceding interruption, the metal at said groove intermediate the interruptions.

3. vThe method of making ascrew closure cap which comprises mounting a cap blank on a roller having an uninterrupted spiral thread forming groove therein, rolling said cap blank along a mating threading section having spaced indentations therein to form a spiral screw thread in the cap and forming ribs across said thread in l0 interruptions being subjected to substantially less strain than the metal'of the portions of the part from the excess metaLfWhch piles up in front -of the roller being bulged successively into said spaced indentations .on said mating threading section during the rolling of a thread to thereby take up the excess metal occasioned in rolling the part of the thread immediately preceding the rib and to supply part of the metal for forming the part of the thread immediately succeedingthe rib.

- LOUIS A. VONTILL` 

